I am often asked if a particular stadium has a "hot gun". The following is a list of corrections/offsets that we use in our data.
These #s use a rolling average of 10 games on either side; so, they are not yet nearly as precise at the very start of the season. Additionally, we use 55' (rather than the gameday standard 50') to compute velo, because it is a more accurate reflection of where the pitcher releases the ball.
For the following table, a negative mph number indicates a cool gun and a positive number indicates a hot gun.
You can also see that several stadiums have relatively large positive values for pfx_x, which indicates that movement is shifted right from the catcher's POV (or left, or negative numbers). Again, these are corrected out of the data displayed on the site.
Because these values change, these values reflect the current corrections applied on 09/25/2016. We also keep historical records on each game's offset for use on our cards and data system.
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